The DNA was discovered at the spot where Stephen was attacked 23 years ago

Police have not been able to identify the girl or woman and a BBC1 Crimewatch appeal is being broadcast tonight to try to trace her on the eve of what would have been his 42nd birthday. It is the first time a female has been linked to the murder scene.

Cops are unsure whether she was with 18-year-old Stephen’s killers or was an innocent passer-by who left the black leather strap before the stabbing in Eltham, South East London, in April 1993.

It is among dozens of items subjected to new forensic tests using updated DNA screening techniques.

Brothers Jamie (left) and Neil Acourt, and Luke Knight (right), were all charged in the 1990s with the murder but were never convicted

Brothers Neil and Jamie Acourt, and Luke Knight, were all charged in the 1990s with the murder but were never convicted.

Det Chief Insp Chris Le Pere said: “While there is no evidence that a woman was at the scene of the attack, I need to establish who this bag belonged to and why it was at the spot where Stephen was attacked.”